
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>提升系统吞吐量的技术 - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>提升系统吞吐量的技术 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，「系统吞öté量」最准确的定义是什么？",
    "options": [
      "系统处理单个请求所需的平均时间。",
      "系统在单位时间内可以处理的请求或任务的数量。",
      "系统中CPU和内存的综合利用率。",
      "系统能够同时处理的最大并发用户数。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确定义，吞吐量是衡量系统单位时间内处理能力的指标，通常以RPS（每秒请求数）或TPS（每秒事务数）来度量。它直接反映了系统的处理效率，区别于响应时间（选项A）、并发数（选项D）或资源利用率（选项C）。",
    "source": "文档中「1.1 吞吐量的定义」部分",
    "hint": "文档开头就解释了吞吐量的概念，并给出了常见的衡量单位。"
  },
  {
    "question": "为什么使用线程池（如`ExecutorService`）可以提升系统吞吐量？",
    "options": [
      "它能让单个线程的执行速度变得更快。",
      "通过复用线程，避免了频繁创建和销毁线程带来的开销。",
      "它能保证所有任务都按提交的顺序严格执行。",
      "它能自动为程序分配更多的CPU核心。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中指出，线程池的核心优势在于复用已创建的线程。这避免了每次处理新任务时都要经历创建和销毁线程的系统开销，从而能更高效地执行大量任务，提升整体吞吐量。",
    "source": "文档中「2.1.1 使用线程池（ExecutorService）」部分",
    "hint": "思考一下，如果不使用线程池，每次来一个新任务都需要做什么？线程池是如何优化这个过程的？"
  },
  {
    "question": "文档中提到，异步处理（例如异步I/O）可以显著提高吞吐量，其主要原因是？",
    "options": [
      "异步处理能够减少网络传输的数据量。",
      "异步处理可以简化编程逻辑，减少代码量。",
      "避免了线程因等待I/O操作完成而产生的阻塞，使其可以继续执行其他任务。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "异步处理的核心优势在于其非阻塞特性。当一个任务发起I/O操作时，执行线程不必原地等待结果，而是可以被释放去处理其他任务。这极大地提高了线程的利用率和系统的整体吞吐量。",
    "source": "文档中「2.2 使用异步处理提升吞吐量」和「2.2.1 异步I/O操作」部分",
    "hint": "文档强调异步处理是一种“避免阻塞”的技术。"
  },
  {
    "question": "在数据库优化方面，使用缓存技术（如Redis）的主要目的是什么？",
    "options": [
      "永久存储所有业务数据，以替代传统关系型数据库。",
      "缓存热点数据，减少对数据库的直接查询次数，从而减轻数据库负担。",
      "保证分布式环境下各个数据库节点之间的数据绝对一致。",
      "加密数据库和客户端之间的通信，提高数据安全性。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档指出，数据库查询是常见的性能瓶颈。通过将热点数据（即频繁访问的数据）存储在高速的内存缓存（如Redis）中，系统可以直接从缓存获取数据，避免了对后端数据库的慢速查询，从而极大提升响应速度和吞吐量。",
    "source": "文档中「2.3.1 使用缓存技术」部分",
    "hint": "想一想，当大量请求查询同样的数据时，哪种方式比每次都去数据库里查找更快？"
  },
  {
    "question": "在高并发场景下，引入消息队列（如RabbitMQ）对提升系统吞吐量起到了什么关键作用？",
    "options": [
      "将同步请求异步化，实现流量削峰，让系统可以平滑地处理大量并发请求。",
      "为系统提供了无限的存储空间来处理请求数据。",
      "减少了客户端与服务端之间的网络延迟。",
      "直接加快了每个业务任务（如库存扣减）的执行速度。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "消息队列通过引入一个中间层，将生产者（请求发送方）和消费者（任务处理方）解耦。在高并发时，它可以作为一个缓冲区，将瞬间涌入的大量请求暂存起来，由后端消费者按照自己的处理能力平稳地拉取和处理。这种“削峰填谷”的能力避免了系统因瞬时压力过大而崩溃，从而提高了整体的稳定性和吞吐量。",
    "source": "文档中「2.5 使用消息队列异步处理请求」和「3.1 异步订单处理」部分",
    "hint": "文档提到消息队列可以“避免瞬间的大量请求对系统造成过大的压力”。"
  },
  {
    "question": "Java 8 引入的 `CompletableFuture` 是如何帮助提升系统吞吐量的？",
    "options": [
      "它通过一种新的垃圾回收机制来优化内存使用。",
      "它提供了一种更安全的替代方案来完全取代传统的`synchronized`关键字。",
      "它支持将多个异步任务以链式调用的方式组合起来，从而实现任务的并行执行并避免阻塞。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中解释道，`CompletableFuture` 提供了一个强大的API来编排异步任务。通过 `thenApply`, `thenAccept` 等方法，可以构建一个非阻塞的任务流水线，其中多个独立的任务可以并行执行，后续任务在前置任务完成后自动触发，从而提高了资源的利用率和系统吞吐量。",
    "source": "文档中「2.2.2 使用`CompletableFuture`实现异步任务链」部分",
    "hint": "思考一下`CompletableFuture`的“链式调用”特性是如何让多个任务协同工作的。"
  },
  {
    "question": "根据文档，负载均衡技术在提升系统吞吐量方面的核心作用是什么？",
    "options": [
      "优化单台服务器内部的数据库查询性能。",
      "将外部请求均匀地分发到多台后端服务器上，避免单台服务器过载，从而提高整个集群的处理能力。",
      "在客户端和服务端之间建立持久连接以减少握手开销。",
      "自动压缩网络请求和响应的数据包大小。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，当单机无法满足高负载需求时，负载均衡可以将请求分摊到多台服务器上。通过这种方式，系统的处理能力不再受限于单个节点的性能，而是可以随着服务器数量的增加而水平扩展，从而显著提升整体吞吐量。",
    "source": "文档中「2.4.1 负载均衡」部分",
    "hint": "文档提到，当系统负载过高时，单机无法满足需求，此时需要使用什么技术来分摊请求？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  